1. Field of the Invention
The present invention relates to a method and an apparatus for controlling the frequency of piezoelectric components. More specifically, the present invention relates to a method and an apparatus for controlling the frequency of piezoelectric components such as piezoelectric ceramic resonators, filters, discriminators, or traps, by removing portions of the electrodes disposed on a piezoelectric substrate, or by adding a frequency control substance on the electrodes.
2. Description of the Related Art
Recently, with piezoelectric components such as filters, there has been a growing need for frequencies having very high precision. Conventionally, the frequency has been controlled by the steps of forming electrodes having frequencies that are somewhat higher than the target or desired frequency on both sides of a piezoelectric substrate, and applying frequency control ink on the electrodes by screen printing or by spray coating to increase the mass thereof. However, in the method described above, concentration of the frequency is too low to improve precision because the quantities of ink applied may vary widely. In addition, in the case of screen printing, the conventional method has another disadvantage in that it may cause cracking of the piezoelectric substrate because this method is based upon contact operation and therefore, the object is subjected to a load.
Accordingly, the applicant of the present invention has proposed a method for carrying out a non-contact frequency control with very high precision (Japanese Unexamined Patent Publication No. 3-289807). According to this method, the marking of a predetermined pattern is carried out by the steps of dividing the pattern to be marked into regions defining a matrix, charging ink particles by applying voltages proportional to the positional information obtained from each region, and directing charged particles of ink to the object to be marked by deflecting them in the electrostatic field. Therefore, a predetermined amount of ink can be applied to a piezoelectric resonator without variations in mass thereof, and thus, frequency control can be carried out with high precision.
When manufacturing piezoelectric components, in order to achieve the economies of mass production, a number of elements are formed first as mother substrates in a first step, and then the mother substrates are cut into individual elements. However, these elements may have differing frequencies even within one mother substrate due to a variety of factors. In such a case, even if the electrically controlled marking method is used as an alternative to screen printing, or other such method, it is difficult to reduce variations of frequencies among individual elements within the mother substrate, though it is possible to reduce variations of frequencies among mother substrates. It is also possible to change the amount of ink to be applied to the elements within a mother substrate on an individual basis according to frequencies thereof, however, it requires longer time because ink must be applied on the element one by one.
To overcome the problems described above, preferred embodiments of the present invention provide a frequency control apparatus for piezoelectric components which controls variations in frequency among individual elements quickly and achieves the economies of mass production, when a plurality of elements are formed within or on a piezoelectric substrate.
The frequency control apparatus for piezoelectric components in accordance with a preferred embodiment of the present invention preferably includes a pattern board disposed on a piezoelectric substrate having a plurality of electrodes disposed thereon and provided with an aperture pattern for selectively exposing the electrodes, a shielding board disposed on the pattern board and provided with a window for selectively exposing aperture patterns on the pattern board, and an electrode removal device arranged to remove portions of the electrodes disposed on the piezoelectric substrate exposed through the aperture pattern on the pattern board and though the window on the shielding board.
In accordance with this preferred embodiment of the present invention, since the electrodes disposed on the piezoelectric substrate are exposed selectively through the aperture pattern on the pattern board and the aperture patterns are exposed selectively through the window on the shielding board, frequency is controlled by selectively exposing electrodes which require frequency control through the aperture pattern according to variations in frequency of respective elements including electrodes from the target frequency, and removing portions of those exposed electrodes.
In addition, in accordance with the present preferred embodiment of the present invention, frequencies of a plurality of electrodes are controlled simultaneously very efficiently by a group of electrodes exposed simultaneously through the window on the shielding board. By repeating frequency control procedures after changing the aperture pattern to be exposed through the window on the shielding board, very precise frequency control is achieved for a plurality of electrodes exposed through the window on the shielding board, and thus, frequencies of individual elements are controlled with high precision.
The frequency control apparatus for piezoelectric components in accordance with another preferred embodiment of the present invention includes a pattern board disposed on a piezoelectric substrate having a plurality of electrodes disposed on the surface thereof and provided with an aperture pattern for selectively exposing the electrodes, a shielding board disposed on the pattern board and provided with a window for selectively exposing an aperture pattern on the pattern board, and frequency control substance coating device arranged to apply a frequency control substance on the electrodes located on the piezoelectric substrate and exposed through the aperture pattern on the pattern board and though the window on the shielding board.
In accordance with the present preferred embodiment of the present invention, since the electrodes provided on the piezoelectric substrate are exposed selectively through the aperture pattern on the pattern board, and the aperture patterns are exposed selectively through the window on the shielding board, frequency may be controlled by selectively exposing electrodes which require frequency control through the aperture pattern according to variations from the target frequency of respective elements which include electrodes, and applying a frequency control substance only on those exposed electrodes.
In addition, in accordance with this preferred embodiment of the present invention, frequencies of a plurality of electrodes may be controlled simultaneously with efficiency by a group of electrodes exposed simultaneously through the window on the shielding board. By repeating frequency control procedures after changing the aperture pattern to be exposed through the window on the shielding board, very accurate frequency control is achieved for a plurality of electrodes exposed through the window on the shielding board. As a result, frequencies of individual elements are controlled with very high precision.
The frequency control apparatus for piezoelectric components in accordance another preferred embodiment of the present invention preferably includes a pattern board disposed on a plurality of piezoelectric substrates having electrodes provided on the surface thereof and provided with an aperture pattern for selectively exposing the electrodes located on a plurality of piezoelectric substrates, a shielding board disposed on the pattern board and provided with a window for selectively exposing aperture pattern on the pattern board, and an electrode removing device arranged to remove portions of the electrodes provided on the piezoelectric substrate and exposed through the aperture pattern on the pattern board and through the window on the shielding board.
In accordance with the present preferred embodiment of the present invention, since the electrodes located on a plurality of piezoelectric substrates can be exposed selectively through the aperture pattern on the pattern board and the aperture pattern can be exposed selectively through the window on the shielding board, frequency control is performed by selectively exposing electrodes which require frequency control through the aperture pattern according to variations in frequency of respective elements which include electrodes, from the target frequency and removing portions of those exposed electrodes.
In addition, in accordance with the present preferred embodiment of the present invention, frequencies of a plurality of piezoelectric substrates are controlled simultaneously very efficiently by a group of electrodes exposed simultaneously through the window on the shielding board. By repeating frequency control procedures after changing the aperture pattern to be exposed through the window on the shielding board, very accurate frequency control is achieved for a plurality of electrodes exposed through the window on the shielding board. As a result, frequencies of elements provided on respective piezoelectric substrates are controlled with very high precision.
The frequency control apparatus for piezoelectric components in accordance with another preferred embodiment of the present invention includes a pattern board disposed on a plurality of piezoelectric substrates having electrodes provided on the surface thereof and provided with an aperture pattern for selectively exposing the electrodes located on a plurality of piezoelectric substrates, a shielding board disposed on the pattern board and provided with a window for selectively exposing predetermined aperture pattern on the pattern board, and a frequency control substance coating device arranged to apply a frequency control substance on the electrodes disposed on the piezoelectric substrate and exposed through the aperture pattern on the pattern board and though the window on the shielding board.
In accordance with the present preferred embodiment of the present invention, since the electrodes located on a plurality of piezoelectric substrates are exposed selectively through the aperture pattern on the pattern board and the aperture patterns are exposed selectively through the window on the shielding board, frequency may be controlled by selectively exposing electrodes which need frequency control through the aperture pattern according to variations in frequency of respective elements including electrodes from the target frequency and applying frequency control substance only on those exposed electrodes.
In addition, in accordance with the present preferred embodiment of the present invention, frequencies of a plurality of piezoelectric substrates are controlled simultaneously and very efficiently by a group of electrodes exposed simultaneously through the window on the shielding board. By repeating frequency control procedures after changing the aperture pattern to be exposed through the window on the shielding board, highly accurate frequency control is achieved for a plurality of electrodes exposed through the window on the shielding board. As a result, frequencies of elements located on respective piezoelectric substrates are controlled with very high precision.
In accordance with another preferred embodiment of the present invention, the frequency control apparatus for piezoelectric components according to other preferred embodiments of the present invention are such that the electrodes are exposed selectively by combining aperture patterns on a plurality of pattern boards.
In accordance with the present preferred embodiment of the present invention, since the electrodes are exposed selectively by a combination of a plurality of pattern boards having aperture patterns thereon, the number of the aperture patterns on each pattern board can be reduced. The total number of aperture patterns on the pattern boards can also be reduced. As a result, the structure of the pattern board is greatly simplified, and the distance of movement of the pattern board can be shortened to achieve rapid control of the frequency.
In accordance with another preferred embodiment of the present invention, the frequency control apparatus for piezoelectric components according to other preferred embodiments described above further includes a shutter for opening and closing the window on the shielding board.
In accordance with this preferred embodiment of the present invention, since the frequency control apparatus for piezoelectric components is provided with a shutter for opening and closing the window on the shielding board, the amount of removal of electrodes or the amount of application of frequency control substance on the electrodes is controlled by controlling the duration of opening and closing of the window, and the frequency of elements is controlled with very high precision.
In accordance with another preferred embodiment of the present invention, the frequency control apparatus for piezoelectric components according to the preferred embodiments of the present invention described above is arranged to linearly move the pattern boards.
In accordance with the present preferred embodiment of the present invention, since the pattern board of the frequency control apparatus for piezoelectric components is linearly moved, the waste region in the pattern boards (waste region between aperture patterns) is reduced in comparison with the apparatus of the type wherein the pattern board is rotatably moved, and the pattern boards can be used effectively with greatly decreased size.
In accordance with another preferred embodiment of the present invention, the frequency control apparatus for piezoelectric components according to the preferred embodiments of the present invention above is arranged to rotationally move the pattern board.
In accordance with the present preferred embodiment of the present invention, since the pattern board is rotationally moved, the aperture pattern board can be moved by, for example, a motor or other suitable mechanism. As a result, the driving system of the pattern board is simplified in comparison with the apparatus of the type wherein the pattern board is moved linearly.
A method for controlling the frequency of a piezoelectric component in accordance with another preferred embodiment of the present invention preferably includes the steps of providing a piezoelectric substrate having a plurality of electrodes provided on the surface thereof, disposing a pattern board having an aperture pattern for selectively exposing electrodes disposed on a piezoelectric substrate, disposing a shielding board having a window for selectively exposing a predetermined aperture patterns on the pattern board, and removing portions of the electrodes disposed on the piezoelectric substrate exposed through the aperture pattern on the pattern board and through the window on the shielding board.
In accordance with another preferred embodiment of the present invention, since the electrodes disposed on a piezoelectric substrate are exposed selectively through the aperture pattern on the pattern board and the aperture patterns are exposed selectively through the window on the shielding board, frequency may be controlled by selectively exposing electrodes which need frequency control through the aperture pattern according to variations in frequency of respective elements which include electrodes, from the target frequency and removing portions of the exposed electrodes.
In addition, in accordance with the present preferred embodiment of the present invention, frequencies of a plurality of electrodes are controlled at the same time with efficiency by a group of electrodes exposed simultaneously through the window on the shielding board. By repeating frequency control procedures after changing the aperture pattern to be exposed through the window on the shielding board, very accurate frequency control is achieved for a plurality of electrodes exposed through the window on the shielding board. As a result, frequencies of individual elements are controlled with very high precision.
A method for controlling the frequency of a piezoelectric component in accordance with another preferred embodiment of the present invention preferably includes the steps of providing a piezoelectric substrate having a plurality of electrodes formed on the surface thereof, disposing a pattern board having an aperture pattern for selectively exposing electrodes formed on the piezoelectric substrate, disposing a shielding board having a window for selectively exposing aperture patterns of the pattern board, and applying a frequency control substance on the electrodes disposed on the piezoelectric substrate and exposed through the aperture pattern of the pattern board and through the window on the shielding board.
In accordance with the present preferred embodiment of the present invention, since the electrodes disposed on the piezoelectric substrate are exposed selectively through the aperture pattern on the pattern board and the aperture patterns are exposed selectively through the window on the shielding board, frequency may be controlled by selectively exposing electrodes which require frequency control through the aperture pattern according to variations in frequency of respective elements which include electrodes, from the target frequency and applying a frequency control substance only to those exposed electrodes.
In addition, in accordance with the present preferred embodiment of the present invention, frequencies of a plurality of electrodes are controlled simultaneously and efficiently by a group of electrodes exposed simultaneously through the window on the shielding board. By repeating frequency control procedures after changing the aperture pattern to be exposed through the window on the shielding board, very accurate frequency control is achieved for a plurality of electrodes exposed through the window on the shielding board. As a result, frequencies of individual elements are controlled with very high precision.
A method for controlling the frequency of a piezoelectric component in accordance with another preferred embodiment of the present invention includes the steps of providing a plurality of piezoelectric substrates having electrodes formed on the surface thereof, disposing a pattern board having an aperture pattern for selectively exposing electrodes formed on a plurality of piezoelectric substrates, disposing a shielding board having a window for selectively exposing aperture patterns of the pattern board, and removing portions of the electrodes formed on the piezoelectric substrate and exposed through the aperture pattern of the pattern board and through the window on the shielding board.
In accordance with the present preferred embodiment of the present invention, since the electrodes disposed on a plurality of piezoelectric substrates are exposed selectively through the aperture pattern on the pattern board and the aperture patterns are exposed selectively through the window on the shielding board, frequencies may be controlled by selectively exposing electrodes which require frequency control through the aperture pattern according to variations in frequencies of respective elements which include electrodes, from the target frequency and removing portions of those exposed electrodes.
In addition, in accordance with the present preferred embodiment of the present invention, frequencies of a plurality of piezoelectric substrates are controlled simultaneously and efficiently by a group of electrodes exposed simultaneously through the window on the shielding board. By repeating frequency control procedures after changing the aperture pattern to be exposed through the window on the shielding board, very accurate frequency control can be achieved for a plurality of electrodes exposed through the window on the shielding board. As a result, frequencies of elements disposed on respective piezoelectric substrates are controlled with very high precision.
A method for controlling the frequency of a piezoelectric component in accordance with another preferred embodiment of the present invention preferably includes the steps of providing a plurality of piezoelectric substrates having electrodes formed on its surface, disposing a pattern board having an aperture pattern for selectively exposing electrodes disposed on a plurality of piezoelectric substrates, forming a shielding board having a window for selectively exposing a predetermined aperture patterns of the pattern board, and applying a frequency control substance on the electrodes formed on the piezoelectric substrate and exposed through the aperture pattern on the pattern board and through the window on the shielding board.
In accordance with the present preferred embodiment of the present invention, since the electrodes provided on a plurality of piezoelectric substrates are exposed selectively through the aperture pattern on the pattern board and the predetermined aperture patterns are exposed selectively through the window on the shielding board, frequency may be controlled by selectively exposing electrodes which need frequency control through the aperture pattern according to variations in frequency of respective elements which include electrodes, from the target frequency and applying a frequency control substance only to those exposed electrodes.
In addition, in accordance with the present preferred embodiment of the present invention, frequencies of a plurality of piezoelectric substrates are controlled simultaneously and efficiently by a group of electrodes exposed simultaneously through the window on the shielding board. By repeating frequency control procedures after changing the aperture pattern to be exposed through the window on the shielding board, very accurate frequency control is achieved for a plurality of electrodes exposed through the window on the shielding board. As a result, frequencies of electrodes formed on respective piezoelectric substrates are controlled with precision.
In accordance with another preferred embodiment of the present invention, in the method for controlling the frequency of a piezoelectric component according to the previously described preferred embodiments, the electrodes are exposed selectively by combining aperture patterns of a plurality of pattern boards.
In accordance with this preferred embodiment of the present invention, since the electrodes are exposed selectively by a combination of a plurality of pattern boards having aperture patterns thereon, the number of the aperture patterns on each pattern board can be reduced. The total number of aperture patterns on the pattern boards can also be reduced. As a result, the structure of the pattern board is greatly simplified, and the distance of movement of the pattern board can be shortened to achieve rapid control of the frequency.
In accordance with this preferred embodiment of the present invention, the method for controlling the frequency of a piezoelectric component according to previously described preferred embodiments of the present invention further includes the step of disposing a shutter for opening and closing the window of the shielding board.
In accordance with this preferred embodiment of the present invention, since the method for controlling frequency of a piezoelectric component includes a shutter for opening and closing the window on the shielding board, the amount of removal of electrodes or the amount of application of frequency control substance on the electrodes is accurately controlled by controlling the duration of opening and closing of the window, and the frequency of elements are therefore controlled with precision.
In accordance with another preferred embodiment of the present invention, the method for controlling frequency of a piezoelectric component according to previously described preferred embodiments of the present invention includes a step of linearly moving the pattern board.
In accordance with this preferred embodiment of the present invention, since the pattern board is linearly moved, the waste region in the pattern boards (waste region between aperture patterns) is greatly reduced in comparison with the apparatus of the type wherein the pattern board is rotationally moved, so that the pattern boards are used effectively to decrease the size of the pattern boards.
In accordance with another preferred embodiment of the present invention, the method for controlling the frequency of a piezoelectric component according to previously described preferred embodiments of the present invention includes the step of rotationally moving the pattern board.
In accordance with this preferred embodiment of the present invention, since the pattern board is rotationally moved, the aperture pattern board can be moved, for example, by a motor or other suitable mechanism, so that the driving system of the pattern board is simplified in comparison with the apparatus of the type wherein the pattern board is moved linearly.
In accordance with another preferred embodiment of the present invention, the method for controlling the frequency of a piezoelectric component according to previously described preferred embodiments, includes the steps of forming the electrodes on the piezoelectric substrate in a matrix, exposing these electrodes through the aperture pattern of the pattern board and through the window of the shielding board on a column-by-column basis, and removing portions of the electrodes or increasing in mass thereof so that the frequency of respective electrodes can be controlled on a column-by-column basis.
Since the present preferred of the present invention preferably includes the steps of forming the electrodes in a matrix and exposing through the aperture pattern on a column-by column basis to control the frequency of respective electrodes on a column-by-column basis, the frequency of electrodes arranged on the piezoelectric board is controlled on a column-by-column basis in orderly sequence.
In accordance with another preferred embodiment of the present invention, the method for controlling the frequency of a piezoelectric component according to previously described preferred embodiments of the present invention preferably includes the steps of arranging piezoelectric substrates having electrodes thereon in a matrix, exposing these electrodes though the aperture pattern on the aperture board and through the window on the shielding board on a column-by-column basis, and removing portions of the electrodes or increasing the mass thereof so that the frequency of respective electrodes are controlled on a column-by-column basis.
Since the method for controlling the frequency of a piezoelectric component according to this preferred embodiment of the present invention includes the steps of arranging the piezoelectric substrates having electrodes thereon in a matrix and exposing the electrodes on these piezoelectric substrates through the aperture pattern on a column-by column basis to control the frequency of respective electrodes on a column-by-column basis, the frequency of the piezoelectric boards having electrodes formed thereon may be controlled on a column-by-column basis in an orderly sequence.
Other features, elements, characteristics and advantages of the present invention will become more apparent with reference to preferred embodiments thereof which are described in detail below with reference to the attached drawings.